There has conventionally been a driving assistance device that warns a driver of the possibility of a collision with a preceding vehicle by outputting a warning sound according to the following distance from the preceding vehicle. For example, a driving assistance device calculates a safe following distance according to the vehicle speed of the own vehicle, successively calculates the degree of risk which is a value obtained by dividing the calculated safe following distance by an actual following distance from the preceding vehicle, and outputs a warning sound in a mode corresponding to the degree of risk. Specifically, a warning sound in a first stage is output when the degree of risk is 1 or more and less than 1.5, and a warning sound in a second stage is output when the degree of risk is 1.5 or more and less than 2.0. Further, a warning sound in a third stage is output when the degree of risk is 2.0 or more.